Oregano oil contains thymol. According to a 2016 review, thymol has antifungal and antibacterial properties. To treat toenail fungus, apply oregano oil to the affected nail twice daily with a cotton swab. Some people use oregano oil and tea tree oil together. Both products are potent and may cause irritation or allergic reaction. Combining them may increase this risk. You can also find oregano oil online.
Other risk factors include perspiring heavily, being in a humid or moist environment, psoriasis, wearing socks and shoes that hinder ventilation and do not absorb perspiration, going barefoot in damp public places such as swimming pools, gyms and shower rooms, having athlete's foot (tinea pedis), minor skin or nail injury, damaged nail, or other infection, and having diabetes, circulation problems, which may also lead to lower peripheral temperatures on hands and feet, or a weakened immune system.
Onychomycosis does not necessarily require treatment. The antifungal medication, terbinafine, taken by mouth appears to be the most effective but is associated with liver problems. Trimming the affected nails when on treatment also appears useful. There is a ciclopirox containing nail polish, but it does not work as well. The condition returns in up to half of cases following treatment. Not using old shoes after treatment may decrease the risk of recurrence.
If you have diabetes, you may have reduced blood circulation and nerve supply in your feet. You're also at greater risk of a bacterial skin infection (cellulitis). So any relatively minor injury to your feet — including a nail fungal infection — can lead to a more serious complication. See your doctor if you have diabetes and think you're developing nail fungus.